DEAR DOCTOR K: I wear corrective glasses for astigmatism, but I don't really understand what astigmatism is.
DEAR READER: Astigmatism means that the cornea of the eye has an irregular shape. The cornea is the clear covering over the lens and the iris. The iris controls how much light enters the eye. The lens focuses the light on the retina, the light-sensitive area at the rear of the eye. The cornea protects these structures and helps to transmit light through the eye.